Entirely combustible inductive primer

ABSTRACT

A pyrotechnical primer for igniting propellant powder for sleeveless ammunition comprises an igniting element ( 4 ) and a coil ( 1 ). The energy required for triggering is transmitted in an electromagnetic manner (inductively). The inductive primer is cost-effective, entirely combustible, easy to produce and is not provided with residues that damage the functioning of the weapons. The primer has a base construction such that the primer can be used in all conventional weapons calibres. To this end, the ignition element ( 4 ) and the coil ( 1 ) are located on a mutual, flat, combustible consumable or support material ( 5 ).

BACKGROUND OF THE INVENTION

The invention relates to a pyrotechnic primer for igniting propellantpowder for sleeveless ammunition, the primer having an ignition elementand a coil, in which the energy required for triggering is transferredby electro-magnetic means (inductively).

The intensified requirement for the use of sleeveless ammunition inrecent years has led increasingly to attempts at solutions comprisingignition systems which operate on the principle of transferring energyto the combustion chamber of a weapon without contact. Solutionsdemonstrating the principle of inductive ignition have been described inthe past and their feasibility has been proved on various weaponssystems.

The principal problem with previous design specifications for inductiveprimers has been with the non-combustible components of the receivingcoil and the electrical ignition elements. This is particularly the casewith relatively small calibre diameters because here unburned remains ofthe primer can form residues either in the cartridge chamber or in thebarrel which will damage the weapon.

BRIEF SUMMARY OF THE INVENTION

The object of the invention is therefore to construct a fullycombustible, inductive primer with a design which is simple andeconomical to manufacture, which does not produce any residues harmfulto the functioning of the weapon and which is suitable for universal usewith all current weapon calibres.

This problem is solved according to the invention in that the ignitionelement and coil are placed on a common, flat, combustible or consumablesupport material.

According to the invention, the entire support material of the primerconsists of combustible or consumable materials such as e.g. paper ornitro-cellulose.

In a preferred embodiment, ends of conductors (printed circuit traceends), which are in one plane, are laid one on top of the other and as aresult of their contacting, a three-dimensional cylindrical coil isformed and, moreover, the remaining printed circuit trace ends formingconnection surfaces (contact points) of the ignition bridge.

It is practical to apply the electrical printed circuit traces to thesupport material using screen-printing, the said traces consisting ofsilver or copper conductive paste.

The inductive primers can be of a columnar or flat design, consisting ofa combustible or consumable electrical ignition element and an inductioncoil with several windings and any desired external geometry, which isapplied to or embedded in a flat single or multi-layer, combustible,insulating support material, it being possible, also, for theelectrically conductive coil material to be designed to be combustibleor consumable.

It is advantageous for the entire inductive primer to be applied in oneplane as a single layer or several layers onto a flexible, combustiblepaper or nitro-cellulose film or another combustible support layer, theentire electrical routing of the conductors or the printed circuittraces consisting, for example, of hardened silver or copper conductivepaste or another metal composition or of non-metallic combustible orconsumable conducting material, which is preferably applied usingscreen-printing or another application process.

The advantage of the above-mentioned invention is to be found in thefact that the inductive primer consists of a single component, whichonly attains its function as a result of shaping and through supply ofincandescent wire, dots of conductive adhesive and the detonator unit,and that it is completely combustible or consumable.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF DRAWINGS

Further characteristics of the invention are to be found in the figures,which are described below.

These show:

FIG. 1 an example of fabrication of a primer according to the invention

FIG. 2 the fabrication process concerned

FIG. 3 the finished primer and

FIG. 4 an alternative example of a flat primer.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows an example of fabrication of a cylindrical receiving coilon combustible support material 5 and printed circuit traces consistingof printed conductive paste with, for example, three windings 1 butwithout the through-contacts in place. The coil windings 1, thethrough-contact points 2, the connection point 3 for the incandescentignition wire and the incandescent wire 4 are illustrated. Theincandescent ignition wire can make the contact with the connectionsurfaces 3, for example, using adhesive or bonding. The geometry,conductor cross-section and number of windings 1 can vary within a broadframework.

FIG. 2 shows the fabrication process for achieving a cylindrical coil bylaying the coil ends 6 together and then making contact between the coilends 6 via the through-contacting points 7, preferably usingelectrically conductive adhesive. In addition, the ends of the paper 5lying one on top of the other can be fixed with NC-adhesive.

FIG. 3 shows the primer ready for installation. Visible are thethrough-contacting points 7, through whose central hole the coil ends 6make contact. The support material 5 around the contact surfaces 3 canbe fixed in a suitable position in the ignition chain because of itsflexibility and connected to a suitable combustible container to holdthe ignition material e.g. using adhesive.

FIG. 4 shows an example of the fabrication of a flat receiving coil oncombustible support material 5′ and printed circuit traces made ofprinted conductive paste with, for example, ten windings. The coilwindings 1′, the through-contact points 7′, the printed circuit traceson the back 8 of the support material 5′ and the connection points 3′ ofthe incandescent ignition wire 4′ can be seen. The geometry, conductorcross-section and number of windings 1′ can vary within a broadframework.

DESCRIPTION OF FUNCTIONING

When a pulse current impinges on a primary coil on the weapon side isstruck by a pulse of current, an alternating magnetic field is generatedand a voltage is induced in the coil of the inductive ignition element,which drives a current because of the electrical resistance of theincandescent wire, which, as a result of conversion into Joulean heat,causes ignition of the detonator unit and thus ignites the propellantpowder.

All the components of the primer are burned or consumed during thisprocess.

1. Pyrotechnic primer for igniting propellant powder for sleevelessammunition, the primer having an ignition element and a coil in whichthe energy required for triggering is transferred by electromagneticmeans (inductively), characterised in that the ignition element and thecoil are situated on a common, flat support material, the entire supportmaterial consisting of combustible or consumable materials, and in thata three-dimensional cylindrical coil is produced by providing conductivetracks on the support material, rolling the support material to form acylinder, and laying opposed conductor ends of the coil one on top ofthe other and making a contact between them, with remaining ends ofprinted circuit traces forming connection surfaces of the ignitionelement.
 2. Primer according to claim 1, characterised in that theentire support material of the primer consists of paper ornitro-cellulose.
 3. Primer according to claim 1, characterised in thatthe coil is applied to the support material by screen-printing silver orcopper conductive paste.
 4. Primer according to claim 1, characterisedin that the entire support material comprises of paper.
 5. Primeraccording to claim 1, characterised in that the entire support materialcomprises of nitro-cellulose.